Today, portable consumer electronic devices are more powerful than ever. For example, small, portable music playback devices can store hundreds, even thousands, of compressed songs and can play back the songs at high quality. With the capacity for so many songs, a playback device can store many songs from different albums, artists, styles of music, etc.
As users desire to store more songs on the portable music player different storage media are being used. A hard disk drive (HDD) has many benefits in terms of capacity, access time, cost. However, HDDs consume power and quickly drain batteries used in a portable music player.
Accordingly, HDDs have power saving modes, such as the STANDBY mode and the SLEEP mode. In both the STANDBY and SLEEP modes the motor is turned off and the disk spins down. Additionally, in SLEEP mode most of the electronic subsystems of the HDD are powered down to save additional power. However, to recover from SLEEP mode the drive must be reset which adds additional time to the recover. Typical recovery times are several seconds to transition from a power-saving mode to an IDLE mode.
In the IDLE mode the HDD is ready to transfer data and the disk is spinning. During reading or writing the HDD is in the ACTIVE mode.
Some HDDs automatically transition to a power saving mode from the IDLE mode if no read or write requests are received during a set time interval, e.g., 30 seconds.
Additionally, jitter is a problem when reading data from an HDD in portable device because the device is subject to jarring or bumping which causes glitches. Further, when the disk is spinning, noise and vibration is present which may be noticeable to a listener.
Accordingly, techniques for extending battery life and reducing jitter and noise in portable music players are being actively developed.
According to one aspect of the present invention, battery life is extended in a portable music player using an HDD to store audio tracks by transitioning the HDD to a power-saving mode when the a track is stored in the play buffer.
According to another aspect of the invention, the HDD is transitioned out of the power-saving mode when the buffer reaches a low threshold level so that a next audio track can be read from the HDD to the buffer before the present track is through playing.
According to another aspect of the invention, the HDD is not transitioned to the power-saving mode if the battery voltage is below a critical level to avoid a large current drain on the batteries occurring when the HDD transitions from the power-saving mode.
Other features and advantages of the invention will be apparent in view of the following detailed description and appended drawings.